The F1's lightweight, form-fitting design provides optimal protection, functionality and comfort. Designed to be worn above or under the jersey. Impact Shield: An exterior of high-impact tested polymer provides optimum protection against debris and collisions. Flow Vents: The grid style air vents provide additional air circulation to help regulate your core temperature. Race Collar Compatible: This product is strategically designed to fit all EVS race collars and most neck braces. Integrated loop straps ensures any EVS race collar stays in place during use. Modularity: A modular design allows for different configurations depending on the user's preferences. Other Features: Click-Tec front closure system ensures adjustability and secure fit. Plush bio-foam liner.